Devices for pulse dosage of liquid microsamples into the flame of an AAS are known, which have a polytetrafluoroethylene funnel which is connected to the unit for spraying the sample by means of a special capillary. The dosage of the solution in volumes of 50-100 microliters is performed manually, using microliter pipettes provided with special movable plastic nozzles (1).
Another known device for automatic pulse dosage of liquid microsamples into the flame of an AAS has been constructed based on the studies performed by Berndt and Jackwerth and is used by Perkin Elmer. It consists of a combination of a Teflon funnel provided with a microliter pipette and a small pump, a system for circular step moving of a table upon which beakers containing samples to be tested are laid. The operation of the device depends on the electronics of the atom absorption spectrophotometer. It permits an automatic dosage of samples of volumes of 50 or 100 microliters.
A manual-acting device for pulse dosage is known, which has a small container with a conical bottom. The sample of a preliminary known volume of 50-500 microliters is pumped only once by the capillary, said capillary being connected to the pulverizer of the AAS.
It is a common disadvantage of the well known automatic devices that these are extemely expensive.
In manual-acting devices for pulse dosage, relatively high cost microliter pipettes with replaceable nozzles are used and the dosage is both unconvenient and tiresome when a large number of samples are to be tested, which results in a lower reproducibility.